Release of mitochondrial cytochrome c and activation of cytosolic caspases induced by myocardial ischaemia

Abstract

It has previously been shown that apoptosis is increased in ischaemic/reperfused heart. However, little is known about the mechanism of induction of apoptosis in myocardium during ischaemia. We investigated whether prolonged myocardial ischaemia causes activation of caspases and whether this activation is related to cytochrome c release from mitochondria to cytosol during ischaemia. Using an in vitro model of heart ischaemia, we show that 60 min ischaemia leads to a significant accumulation of cytochrome c in the cytosol and a decrease in mitochondrial content of cytochrome c but not cytochrome a. The release of cytochrome c from mitochondria was accompanied by activation of caspase-3-like proteases (measured by cleavage of fluorogenic peptide substrate DEVD-amc) and a large increase in number of cells with DNA strand breaks (measured by TUNEL staining). Caspase-1-like proteases (measured by YVAD-amc cleavage) were not activated during ischaemia. Addition of 14 microM cytochrome c to cytosolic extracts prepared from control hearts induced ATP-dependent activation of caspase-3-like protease activity. Our data suggest that extended heart ischaemia can cause apoptosis mediated by release of cytochrome c from mitochondria and subsequent activation of caspase-3.

Blockade of Electron Transport before Cardiac Ischemia with the Reversible Inhibitor Amobarbital Protects Rat Heart Mitochondria

“…Thus, prevention of electron flow into complex III via inhibition of complex I protects mitochondrial function and decreases oxidant generation. Myocardial ischemia increases apoptosis , which becomes increasingly evident during reperfusion (Borutaite et al, 2001;Chen et al, 2001). Cytochrome c loss from mitochondria facilitates apoptosis (Borutaite et al, 2001;Chen et al, 2001).…”

“…Mitochondrial dysfunction contributes to myocardial injury during ischemia and reperfusion (Borutaite et al, 2001;Lesnefsky et al, 2001b;Lesnefsky and Hoppel, 2003). Ischemia damages the electron transport chain leading to decreased rates of oxidative phosphorylation (Lesnefsky et al, 1997(Lesnefsky et al, , 2001a.…”

Tetramethylphenylenediamine protects the isolated heart against ischaemia‐induced apoptosis and reperfusion‐induced necrosis

“…In general, it is found that relatively short periods of ischaemia induce apoptosis, longer periods of ischaemia induce necrosis, while reperfusion induces necrosis with additional apoptosis (Schumer et al, 1992;Fliss and Gattinger, 1996;Kametsu et al, 2003), but the relation between these events remains unclear. We and others have shown that ischaemia induces rapid cytochrome c release from mitochondria in rat perfused hearts, followed by caspase activation and nuclear apoptosis (De Moissac et al, 2000;Borutaite et al, 2001), and these events are prevented by inhibiting the mitochondrial permeability transition pore (Borutaite et al, 2003). Cytochrome c release activates apoptosis by binding to a cytosolic adaptor protein, APAF-1, which then recruits and activates procaspase-9 within the apoptosome (Li et al, 1997).…”

“…We and others have shown that ischaemia induces rapid cytochrome c release from mitochondria in rat perfused hearts, followed by caspase activation and nuclear apoptosis (De Moissac et al, 2000;Borutaite et al, 2001), and these events are prevented by inhibiting the mitochondrial permeability transition pore (Borutaite et al, 2003). Cytochrome c release activates apoptosis by binding to a cytosolic adaptor protein, APAF-1, which then recruits and activates procaspase-9 within the apoptosome (Li et al, 1997).…”

Mitochondrial Transcription Factor A's role in heart failure.

“…ROS can further oxidize proteins, resulting in aggregation (Borutaite et al 2001 (Minematsu et al 2011). Interestingly, prolonged stimulation of TLR-4 leads to translocation of NFAT into the mitochondria, which reduces ATP production .…”